Well here's one for you: My setup is K3 to wattmeter to dummy load.
The K3 says 100w If the external wattmeter is: MFJ 949E tuner/SWR meter (tuner out of circuit) it says 100w cheapo Radio Shack SWR meter 100w LP 100A digital wattmeter says 70 watts Elecraft W2 says 70 watts Yes, I have run the transmitter calibration routine in the K3 Utility program. SWR in all three cases is nominal 1:1 The result is the same to a real antenna although the SWR is not 1:1 What could be causing the external-sensor type wattmeters to read low? Buck k4ia K3 # 101 On 1/2/2012 10:14 PM, Ron D'Eau Claire wrote: > Quite right. > > There a couple of impedance transformations that occur between the > collectors (or plates) of the power amplifiers and the antenna. The first is > done by the output filters. In modern rigs, they are fixed tuned and > designed in common Ham rigs to convert the impedance at the collectors to 50 > ohms, resistive. > > If your antenna presents that impedance, no further conversion is necessary. > But many antennas don't. > > In the "old" days the output network was adjustable and we simply did the > necessary adjustments and all was good. > > Nowadays, with fixed tuned amplifier output networks, we need another > matching network to handle the conversion when the antenna doesn't present a > 50 ohms resistive load. > > Enter the "antenna tuner" that converts what the antenna shows to the 50 > ohms needed by the output filter. The built in SWR meter displays the SWR on > the link between the tuner and the output filter. > > Ron AC7AC > > -----Original Message----- > From: elecraft-boun...@mailman.qth.net > [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Tom Azlin N4ZPT > Sent: Monday, January 02, 2012 6:19 PM > To: elecraft@mailman.qth.net > Subject: Re: [Elecraft] K3 Internal Tuner Question > > Thanks Matthew. I should not have spoken like that. Should just > have said the meter in the line would not change just because a radio > tuner transformed impedance to make the radio happy. 73, tom n4zpt > > On 1/2/2012 9:11 PM, Matthew Pitts wrote: >> Tom, >> >> All an antenna tuner does is show the radio the load it expects; the >> SWR will still be high at the output of the tuner, and an SWR meter >> in the coax at that output will show it as it actually is at that >> point, not as it is on the input of the tuner/output of the radio. >> >> Matthew Pitts N8OHU > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
